From: Konstantin Khorenko <khorenko@virtuozzo.com>
To: "Denis V. Lunev" <den@openvz.org>
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v2 2/3] dm-qcow2: fix backward merge of an inner image racing its reads
Date: Wed, 04 Nov 2026 17:59:49 +0100 [thread overview]
Message-ID: <179381158915.2686233.3256524369858117621.b4-review@b4> (raw)
In-Reply-To: <20261103090813.166986-3-den@openvz.org>
I won't apply this version, please send v2 with the changes below.
On 11/3/26 10:08, Denis V. Lunev wrote:
> Pause submission and switch the inflight refs for every image. The
> pause flag is only tested on the top image, where all qios enter, so
> pause that one; clearing the flag of an inner image paused the inner
> image itself, which held nothing back.
Item 3 of the cover letter reply: say here that guest I/O to the top
image is now paused for the inflight ref switch when a merge of an
inner image starts or stops. That is fine, a merge of the top image
always cost the same, but the message should say it.
> + * A lower image has no writes, but it is read by
> + * qios of the top one, so stop the top image even then.
Item 2 of the cover letter reply: write "no guest writes". A writable
inner image is still written by qcow2_break_l1cow() and by the merge
itself.
With that fixed:
Reviewed-by: Konstantin Khorenko <khorenko@virtuozzo.com>
--
Konstantin Khorenko,
Virtuozzo Linux Kernel Team
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next prev parent reply other threads:[~2026-11-04 17:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-03 9:08 [Devel] [PATCH hci-8.1 v2 0/3] dm-qcow2: fix merges not stopping the users of the images they change Denis V. Lunev
2026-11-03 9:08 ` [Devel] [PATCH hci-8.1 v2 1/3] dm-qcow2: fix a failed refcount table relocation leaking md pages Denis V. Lunev
2026-11-03 9:13 ` no-reply
2026-11-03 9:27 ` Denis V. Lunev
2026-11-04 16:59 ` Konstantin Khorenko
2026-11-03 9:08 ` [Devel] [PATCH hci-8.1 v2 2/3] dm-qcow2: fix backward merge of an inner image racing its reads Denis V. Lunev
2026-11-03 9:13 ` no-reply
2026-11-04 16:59 ` Konstantin Khorenko [this message]
2026-11-03 9:08 ` [Devel] [PATCH hci-8.1 v2 3/3] dm-qcow2: fix SEEK_HOLE/SEEK_DATA using an image freed by a merge Denis V. Lunev
2026-11-03 9:15 ` no-reply
2026-11-04 16:59 ` Konstantin Khorenko
2026-11-04 13:15 ` [Devel] [PATCH hci-8.1 v2 0/3] dm-qcow2: fix merges not stopping the users of the images they change Andrey Zhadchenko
2026-11-04 16:59 ` Konstantin Khorenko
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